Filoviruses (e.g., Ebola virus and Marburg virus) are among the most lethal and destructive viruses. They cause severe, often-fatal viral hemorraghic fevers in humans and nonhuman primates (e.g., monkeys, gorillas, and chimpanzees). Filoviruses are of particular concern as possible biological weapons since they have the potential for aerosol dissemination and weaponization.
The incubation period for Filovirus infection ranges from 2 to 21 days. The onset of illness is abrupt and is characterized by high fever, headaches, joint and muscle aches, sore throat, fatigue, diarrhea, vomiting, and stomach pain. A rash, red eyes, hiccups and internal and external bleeding may be seen in some patients. Within one week of becoming infected with the virus, most patients experience chest pains and multiple organ failure, go into shock, and die. Some patients also experience blindness and extensive bleeding before dying.
Filoviridae are a family of RNA viruses. Two members of the Filoviridae family have been identified: Ebola virus and Marburg virus. There is one identified strain of Marburg virus and four identified subtypes (i.e., strains) of Ebola virus: Ebola-Zaire, Ebola-Sudan, Ebola-Ivory Coast (i.e., Ebola-Tai), and Ebola-Reston. The exact origin, locations, and natural habitat of Filoviridae unknown. However, on the basis of available evidence and the nature of similar viruses, it is postulated that Filoviridae are zoonotic (i.e., animal-borne) and are normally maintained in an animal host that is native to the African continent.
Because the natural reservoir of the virus is unknown, the manner in which the virus first appears in a human at the start of an outbreak has not been determined. It is hypothesized that the first patient becomes infected through contact with an infected animal. After the first case-patient in an outbreak setting is infected, the virus can be transmitted in several ways. People can be exposed to the virus from direct contact with the blood and/or secretions of an infected person. Thus, the virus is often spread through families and friends because they come in close contact with such secretions when caring for infected persons. People can also be exposed to the virus through contact with objects contaminated with infected secretions (e.g., needles or syringes). All Filoviridae species have also displayed the ability to be spread through airborne particles (i.e., via aerosol).
Prevention and treatment for Filovirus infection presents many challenges. Because the identity and location of the natural reservoir of the viruses are unknown, there are few effective preventative measures. There is currently no treatment for Filovirus infection. Patients receive supportive therapy, i.e., electrolyte and fluid balancing, oxygen, blood pressure maintenance, and treatment for any secondary infections.
Thus, there is a need for compositions and methods for treating and preventing filovirus infection, e.g., by specifically modulating filovirus gene expression. The present invention addresses these and other needs.